Method for the separation of cobalt and nickel from solutions



Nov. 22, 1949 R. B. SCHAAL METHOD FOR THE SEPARATION OF COBALT ANDNICKEL FROM SOLUTIONS Filed Sept. 30, 1943 ICoO'I STEP l [Gamml Ni(0u),+HCI a 606014)?, Ni (muy CaCl;L

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. P03537' B. C/-)L CALCINEI BY- Gf/M KW/M Patented Nov. 22, 1949 lMETHODFOR THE SEPARATION OF COBALT AND NICKEL FROM SOLUTIONS Robert B. Schaal,Independence, Ohio, assignor to Eerro -Enamel Corporation, Cleveland,Ohio, a

.corporation of Ohio Application September 30, 1943, Serial No. 504,382

6 Claims. :1

This invention relates as indicated to the method for the separation ofcobalt and nickel from solutions, and is especially useful as a furtherstep in the generaleprocessy of refining cobalt ores as disclosed in my-copending application, Serial No. 371,509, led December 24, 1940, nowPatent No. 2,379,659.

The process of my said .application concludes with a double chloridesolution of cobalt and nickel. Such solutionmay Yalso contain minoramountsY of other chlorides with which, however, the present processis-notconcerned.

It is a principal object ofthefpresent invention to provide a process by.which the cobalt and nickel components of a double chloride solutionmay be separatedtherefrom in substantially pure form with eachcomponent, i.l e.,nickel.or. cobalt, uncontaminatedby any 'substantialamounts of the other component.

Other objects of mylinvention Awill appear as the description proceeds.

To the accomplishment'of the foregoing and related ends, saidinventionJthen comprises the features hereinafter fullyfdescribed andparticu- 25 larly pointed out inthe.claims,'the following descriptionsetting forthfinrdetail-,certain illustrativeembodiments of theinvention, these being indicative, however,of.,but alfeW of the variousWays in which the principlerof ,the invention 30 may be employed.

Broadly stated, thisinvention ycomprises the process which ischaracterizedin that the cobalt and nickel components are firstconverted to the corresponding hydroxide. Substantially all of thenickel hydroxide'isI then reconverted along with only some ofthe'cobaltihydroxide into the corresponding chlorides, permitting arecovery at this point of a substantial-amount of the cobalt in the formof the hydroxideyand then recon- 10 responding hydroxide.

first treated by bubbling chlorine V'gas therethrough or in any othersuitablefashion, in the presence of an alkalisuch as calcium carbonateresulting in the following representative .reac- 5 tion:

1'5 the conversion ,of the cobalt component `since duplication ofsuch-reactionsforthe nickel component is believed unnecessarytothoseskilled in the art.

This chlorination-step .is carriedon With the 20 presence in thesolution-ofa-suicient amountof an alkali such as. calcium:carbonate soas to also combine with all of the HC1 formed during the conversion ofall of the chlorides in this lirst chlorinating step. 4Therepresentative reaction by Which-,the calciumfcarbonate'thus removes orsequesters the HC1 is as follows:

After using up all the alkali by Step 1, `Step 2 comprises chlorinationin'the absence of alkali.

'The excesschlorinepassed into the solution by this overchlorinationstep combines with water forming hypochloricfacid and hydrochloric acidin accordance with the followingrepresentative reaction:

Verting the chlorides thus formed so as tvpref tion C above makes thelsolution progressively cipitate substantially all of the cobalt as thehydroxide, and only some of the nickel as the hydroxida'leaving Vforfurther reconversion and more acid ras y the 1.chlorination stepprogresses The-cobalt hydroxide land nickel hydroxide; present aresoluble irl-:such yacid vsolution in accordreeovery a substantia1 amountof the nickel'free *.45 vvSuf-10e with the follovvlfleVer representativeequation;

from anysubstantial amount of cobalt.

For a'fuller understanding of my invention, the process may be explainedby having detailed reference to the various steps performed.

In said annexed flow sheet Step 1 The double chloride solution ofnickelchlori'de and cobalt chloride available-for example from theprocess ofnmy said.. copending application is The nickel. hydroxideis-more-soluble than the cobalt hydroxide in the weakly acid solutionY50 pformed during the early stages of overchlorinathat `while thenickel hydroxide vis thus more 55 `soluble in the weaker acid' solution,nevertheless,

by the time substantially all of the nickel hydroxide has thus beendissolved, a small portion of the cobalt hydroxide will also have beendissolved.

Step 3 The solution resulting from the overchlorination Step 2 abovewill contain substantially all of the nickel in the form of nickelchloride and only a minor proportion of the cobalt in the form of cobaltchloride. The major proportion of the cobalt will be left asprecipitated cobalt hydroxide, which may be removed by iiltration.

This step, therefore, is the one which yields the segregated cobalt inthe form of the hydroxide which is substantially free from nickel andwhich may be converted to cobalt oxide by being dried and calcined.

Step 4 The filtrate resulting from Step 3 above is acid, and saturatedwith chlorine due to the overchlorination Step 2 above. In this fourthstep, a suicient amount of an alkali or other HCl sequestering reagent,such as calcium carbonate, is added to the iiltrate in an amountsufficient to neutralize the excess acid, thus permitting the convertingof substantially all of the cobalt chloride and only some of the nickelchloride into the corresponding hydroxides. Because the nickel chlorideis more soluble in the weaker acid solution, the cobalt chloride willrst be converted to the corresponding hydroxide as the HC1 sequesteringreagent removes the hydrochloric acid from the solution. Accordingly, byadding an excess amount of the HC1 sequestering reagent, all of thecobalt chloride will be converted to cobalt hydroxide, and, dependingupon the nal acidity after the reaction ends a small but minor amount ofthe nickel chloride will be converted into the corresponding hydroxide,leaving a major proportion of the nickel chloride in solution.

Step

The product of Step 4 above is then filtered, removing from the solutionsubstantially all of the cobalt in the form of the hydroxide, and only aminor amount of the nickel in the form of the hydroxide, leaving in thefiltrate substantially no cobalt chloride but a substantial amount ofnickel chloride.

Step 6 The filtrate resulting from Step 5 above, and containing asubstantial amount of the nickel in the form of the chloride andsubstantially no cobalt, is then precipitated with sodium hydroxide,whereby the nickel chloride is converted to the hydroxide as follows:

The suspension of nickel hydroxide resulting from Step 6 above is thenfiltered, separating the nickel hydroxide. This is the step which yieldsthe segregated nickel in the form of the hydroxide substantially freefrom cobalt. The nickel hydroxide thus segregated may then be convertedto the oxide by drying and calcining.

Step 8 It will be recalled that in Step 4 above, there was formed amixture of cobalt and nickel hydroxides which were then removed byfiltering in Step 5. This mixture of hydroxides in this Step 8 is thenrepulped with water and added to fur- `4 ther cobalt-nickel chlorideliquor used in Step 1 above, so that the amounts of cobalt and nickelincluded in this mixture of hydroxides will pass through the remainingsequence of steps and be ultimately recovered either as cobalt in Step3, or as nickel in Step 7.

As an indication of relative quantities of the materials in the varioussteps as above outlined, in a commercial operation in accordance withthe process of my invention, the following is submitted:

Analysis of combined chloride solution (mother liquor) Co2.05 g./l.Ni-10.40 g./l. Volume of chloride solution taken, 1000 gal. 0;

Mixed cake from previous chlorination; weight taken wet 12.7#. Analysis:

Co13.1% Ni-2.6% H2O-62% CaCO3-8% Weights added in mixed cake:

Co-1.66# Ni-.33# CaCOs-LOZ# Totals added as solution plus mixed cake:

Co--18.76# Ni-87.13# CaCOa--1.02#

Calcium carbonate added in addition to above, 46.6#. Chlorine added,35#, agitated 15 min.

On filtering and washing the following products were obtained: (a)Liquid, 1205 gal., containing Co.18 gm./1.=1.8# Ni-8.65 gm./1.=87.0#

(b) Filter cake, 88.7#, containing CO--19.21 17.04# Ni-.16 :.14#H2O-63.0

To the 1205 gal. liquid (a) was added 35# CaCOs (Step 4) and agitateduntil the liquid contained no further cobalt. It was then ltered andwashed, obtaining:

(c) Liquid iiltrate, 1378 gal., containing Co-None Ni-7.5 gm./l.=86.3#Ni

The cake (a) on drying, calcining, and pulverizing yielding 23.0# ofblack oxide powder, analyzing:

rIhev cake contained, 2in Aaddition;y small quantiwell as a little S102and A1203, theseimpurities being due to slightly imperfect prior fseparation `and impuritiesintroducedin the calcium carbonate.

The nickel Asolution (c) was ,precipitated by caustic soda, ltered,washed by several repulpings and intervening illtrations, dried,calcined, pulverized and weighed. It produced a silvery grayspowder,weighing 109#,and analyzing:

There were small quantities of Fe, Cu, CaO, CO2,-Cl2and alkalies inthisacake with traces .of Mn and Pb. The losses are.due to-.themechanical operations indicated.

I am aware of the-fact-that prior Workers in the art haveAsuggested"that when chlorine is passed "throughA a cold-solutionlcontaining cobalt and nickel, and'- chlorides rinthelpresence-offcalcium carbonate, cobaltic hydroxide precipitatesleaving nickel chloride in solution. Strictly speaking, however, theseprior art processes are useful only in the case of solutions so diluteas to be of no commercial application. Otherwise, some nickelco-precipitates with the cobalt.

The process which I have provided, however, insures sequentialseparation of the nickel and cobalt, without either being contaminatedto any substantial extent by the other, irrespective of the relativeconcentrations of the two in the starting material.

Other modes of applying the principle ofthe invention may be employed,change being made as regardsthe details described, provided the featuresstated in any of the following claims or the equivalent of such beemployed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. The method of separating cobalt from a double chloride solution ofcobalt and nickel which comprises: (a) chlorinating the solution, in thepresence of a stoichiometric amount of calcium carbonate required toreact with the hydrochloric acid produced, suicently to precipitatesubstantially all of the chlorides of cobalt and nickel present in thesolution as the corresponding hydroxides, (b) further chlorinating to anextent suiiicient to redissolve substantially all of the nickelhydroxide and only a minor amount of the cobalt hydroxide as thecorresponding chlorides and with the production of free hydrochloricacid, and then (c) separating the remaining cobalt hydroxide from thesolution.

2. The method of separating cobalt and nickel from a double chloridesolution thereof which comprises: (a) chlorinating the solution, in thepresence of a stoichiometric amount of calcium carbonate required toreact with the hydrochloric acid produced, sufficiently to precipitatesubstantially all of the chlorides of cobalt and nickel present in thesolution as the corresponding hydroxides, (b) further chlorinating to anextent sucient to redissolve substantially all of the nickel hydroxideand only a minor amount of the cobalt hydroxide as the correspondingchlorides and with the production of free hydrochloric acid, (c)separating the remaining cobalt hydroxide from the solution, and then(d) recovering the nickel from the filtrate.

3. The method of separating cobalt and nickel from a double chloridesolution thereof which comprises: (a) chlorinating the solution, in thepresence of a stoichiometric amount of calcium carbonaterequired.toreact withthe hydrochloric acid produced, sufficiently to precipitatesubstantially all of the chlorides of cobalt and nickel present in thesolution as the corresponding hydroxides, (b) 'further chlorinating toan extent sufficient to redissolve substantially all of the nickelhydroxide and only a minor amount of the cobalt hydroxide as thecorresponding chlorides and with the production oi free hydrochloricacid, (c) ltering the remaining cobalt hydroxide from the solution, (d)converting substantially all of the cobalt chloride and some of thenickel chloride in the iiltrate into the corresponding hydroxides byadding calcium carbonate, (e) filtering from the solution the cobalthydroxide and nickel hydroxide so formed, and then (f) recovering thenickel from the ltrate.

4. The method of separating cobalt and nickel from 'a double chloridesolution thereof which comprises: (a) chlorinating the solution, in thepresence of a stoichiometric amount of calcium carbonate required toreact with the hydrochloric acid produced, sufficiently to precipitatesubstantially all of the chlorides of cobalt and nickel present in thesolution as the corresponding hydroxides, (b) further chlorinating to anextent sufficient to redissolve substantially all of the nickelhydroxide and only a minor amount of the cobalt hydroxide as thecorresponding chlorides and with the production of free hydrochloricacid, (c) filtering the remaining cobalt hydroxide from the solution,(d) converting substantially all of the cobalt chloride and some of thenickel chloride in the filtrate into the corresponding hydroxides byadding calcium carbonate, (c) iiltering from .the hydroxide so formed,leaving in the filtrate substantially no cobalt chloride but asubstantial amount of nickel chloride, converting substantially all ofthe nickel chloride into the corresponding hydroxide by adding sodiumhydroxde, and then (g) filtering the nickel hydroxide from the productof step (f).

5. The method of separating cobalt and nickel from a double chloridesolution thereof which comprises: (a) chlorinating the solution, in thepresence of a stoichiometric amount of calcium carbonate required toreact with the hydrochloric acid produced, sufliciently .to precipitatesubstantially all of the chlorides of cobalt and nickel present in thesolution as the corresponding hydroxides, (b) further chlorinating to anextent suicient to redissolve substantially all of the nickel hydroxideand only a minor amount of the cobalt hydroxide as the correspondingchlorides and with the production of free hydrochloric acid, (c) lteringthe cobalt hydroxide precipitate from the solution, (d) adding to thefiltrate an amount of calcium carbonate sucient to neutralize the freehydrochloric acid from the previous step and substantially all of thecobalt chloride and only a small but minor amount of the nickel chlorideare converted into the corresponding hydroxides, (e) iiltering from thehydroxide so formed, leaving in the filtrate substantially no cobaltchloride but a substantial amount of nickel chloride, (f) convertingsubstantially all of the nickel chloride in the filtrate into nickelhydroxide by adding sodium hydroxide, (g) filtering the nickel hydroxidefrom the product of step (f), and then (h) repulping the hydroxidemixture removed by step (e) for addition to further liquor used in step(a).

6. The method of separating cobalt and nickel from a double chloridesolution thereof which comprises: (a) chlornating the solution, in thepresence of a stoichiometric amount of calcium carbonate required toreact with the hydrochloric acid produced, sufficiently to precipitatesubstantially all of the chlorides of cobalt and nickel present in thesolution as the corresponding hydroxides, (b) in the absence of calciumfurther chlorinating to an extent sufficient to redissolve substantiallyall of the nickel hydroxide and only a minor amount of the cobalthydroxide into the corresponding chloride with the production of freehydrochloric acid, and then (c) filtering the remaining cobalt hydroxidefrom the solution, (d) adding to the filtrate an amount of calciumcarbonate sucient to neutralize excess hydrochloric acid substantiallyall of the cobalt chloride and only some of the nickel chloride beingconverted into corresponding hydroxides, (e) filtering from thehydroxide so formed, leaving in the filtrate substantially no cobaltchloride but a substantial 20 REFERENCES CITED The following referencesare of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,365,358 Udy Jan. 11, 19211,596,253 Harshaw Aug. 7, 1926 OTHER REFERENCES Treadwell & Hall,Analytical Chemistry, vol. I, 1930, pages 182, 183. 188 and 189.

